Financial instruments (Details) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2011	Oct. 31, 2010
Summarized values by currency and forward exchange contracts outstanding
Notional amount of foreign currency derivative sale contracts	$ 70,851	$ 36,449
Foreign currency derivative fair value sale contracts	70,739	37,406
Notional amount of foreign currency derivative purchase contracts	193,026	244,741
Foreign currency derivative fair value purchase contracts	193,290	257,350
Euro [Member]
Summarized values by currency and forward exchange contracts outstanding
Notional amount of foreign currency derivative sale contracts	10,920	17,145
Foreign currency derivative fair value sale contracts	10,967	17,601
Notional amount of foreign currency derivative purchase contracts	88,209	171,870
Foreign currency derivative fair value purchase contracts	87,736	181,430
Pound sterling [Member]
Summarized values by currency and forward exchange contracts outstanding
Notional amount of foreign currency derivative sale contracts	29,381	0
Foreign currency derivative fair value sale contracts	29,465	0
Notional amount of foreign currency derivative purchase contracts	56,028	25,832
Foreign currency derivative fair value purchase contracts	56,515	26,576
Japanese Yen [Member]
Summarized values by currency and forward exchange contracts outstanding
Notional amount of foreign currency derivative sale contracts	16,723	12,947
Foreign currency derivative fair value sale contracts	16,416	13,260
Notional amount of foreign currency derivative purchase contracts	15,788	18,678
Foreign currency derivative fair value purchase contracts	15,566	19,490
Others [Member]
Summarized values by currency and forward exchange contracts outstanding
Notional amount of foreign currency derivative sale contracts	13,827	6,357
Foreign currency derivative fair value sale contracts	13,891	6,545
Notional amount of foreign currency derivative purchase contracts	33,001	28,361
Foreign currency derivative fair value purchase contracts	$ 33,473	$ 29,854